Chromium(VI) is a highly carcinogenic and mutagenic agent. It is believed that Cr(VI) generates long-lived hypervalent chromium species which is responsible for DNA damage. A long-term goal of the project is to understand how hypervalent chromium species initiates the degradation of the DNA and induces cancer. Since hypervalent chromium species are powerful oxiding agents, DNA damage through an oxidative cleavage is a prime suspect. It is proposed to investigate the reactions of deoxynucleotides with bis(2-hydroxy-2-ethyl-butyrato)-oxochromate(V) and (IV) ions with particular emphasis in characterizing intermediates and products. These chromium(V) and (IV) ions with particular emphasis in characterizing intermediates and products. These chromium(V) and (IV) complexes would serve as model carcinogens. Reactions with deoxynucleotides will be compared with those of oxynucleotides and hence the role of hydrogen at 2-site can be understood. Reactions with oligonucleotides containing various base sequence will be examined in order to understand any preference toward a given sequence. The experimental methods include HPLC to separate products, P-31 NMR spectroscopy to characterize phosphate species, esr spectroscopy to monitor and characterize radicals captured by spin traps and other esr active paramagnetic intermediates and products, and dynamic magnetic susceptibility to characterize paramagnetic intermediates and products. Rate measurements along with the characterization of intermediates and products would aid to elucidate mechanisms of DNA damage by the carcinogenic chromium species.